Add documentation for words related to string and numeric literals

documentation.frt

@@ -12,3 +12,70 @@ Drop the topmost element of the stack
 ( a b -- b a )
 Swap two topmost elements of the stack
 " doc-word
+
+' read-oct-digit g"
+( -- digit )
+Read one octal digit
+" doc-word
+
+' read-hex-digit g"
+( -- digit )
+Read one hexadecimal digit
+" doc-word
+
+' read-digit g"
+( -- digit )
+Read one decimal digit
+" doc-word
+
+' ." g"
+( -- )
+Print string literal
+
+This word reads the string until it meets a double quote, stores it in
+the word being defined and prints it.
+" doc-word
+
+' g" g"
+( -- string )
+Store string literal in global data segment
+
+This word reads the string until it meets a double quote, stores it in
+the global data segment and pushes the pointer to it onto the stack.
+" doc-word
+
+' " g"
+( -- string )
+Read string literal with escape sequences
+
+This word reads the string until it meets a double quote, stores it in
+the word being defined and pushes the pointer to it onto the stack.
+" doc-word
+
+' _" g"
+( -- string )
+Read string literal without expanding escape sequences
+
+This word reads the string until it meets a double quote, stores it in
+the word being defined and pushes the pointer to it onto the stack.
+" doc-word
+
+' 0x g"
+( -- number )
+Read hexadecimal literal
+" doc-word
+
+' 08x g"
+( -- number )
+Read octal literal
+" doc-word
+
+' O_CREAT g"
+( -- 0x40 )
+Push a flag O_CREAT (create new file if pathname does not exist) onto stack
+" doc-word
+
+' O_APPEND g"
+( -- 0x400 )
+Push a flag O_APPEND (seek to the end of file) onto stack
+" doc-word